--> ABSTRACT: Integration of Geological and Reservoir Engineering Data for Prediction of Drainage Patterns in Fractured Reservoirs, by H. Harstad, L. W. Teufel, and J. C. Lorenz; #91021 (2010)

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Integration of Geological and Reservoir Engineering Data for Prediction of Drainage Patterns in Fractured Reservoirs

HARSTAD, HUGO, LAWRENCE W. TEUFEL, and JOHN C. LORENZ

From a reservoir engineering perspective the primary objective for characterizing natural fractures is to provide representative fracture permeabilities for the reservoir. Unfortunately, predicting fluid-flow response of fractured reservoirs is difficult because of the variability of the three dimensional fracture networks, permeability anisotropy, and interaction of fracture and matrix permeability. Integration of geological data from outcrops, logs and core with production and well testing data provides the most reliable approach to fracture characterization and fluid flow simulation. This approach has been applied to the Mesaverde formation were pressure interference was combined with fracture characterization from outcrops studies. The pressure interference provides information on the continuity, transmissibility, storage and anisotropy of the formation. Geological data gives information on fracture spacing and distribution. Fluid flow simulation confirm that fractures not only enhance the overall porosity and permeability of these reservoirs, but fractures also create significant permeability an isotropy. Permeability an isotropy causes the drainage area around the wells to be elliptical. The aspect ratio of the elliptical drainage area in these reservoirs is determined bye the magnitude of the permeability an isotropy and reservoir porosity. These results demonstrate that well spacing of 320 acre or 20 acre squares based on radial drainage is not relevant when fractured reservoirs have permeability anisotropy of up to 1000 to 1. Economic optimization of infill drilling using fewer wells can be accomplished if field development is based on elliptical drainage areas that lead to a reduction in drainage overlap of adjacent wells and prevents leaving undrained areas.

AAPG Search and Discovery Article #91021©1997 AAPG Annual Convention, Dallas, Texas.